Liquid crystal displays (LCD's) are becoming more and more popular and widely used in many different types of electronic equipment including portable computers and portable data terminal devices. With present technology, LCD's providing the best performance (clarity, brightness, angle vision, resolution etc.) and the greatest size are made of glass and are very sensitive to shock and pressures which arise through normal use of portable devices. Glass LCD's are made of a glass "sandwich" comprising upper and lower glass sheets with liquid crystal elements sandwiched therebetween. In addition to the glass sandwich there is normally an upper polarizer sheet of polarized plastic film stuck to the upper glass sheet by continuous adhesive and a lower polarizer of transparent or transflective or reflective plastics film stuck to the underside of the lower glass sheet by continuous adhesive.
Present arrangements for ruggedizing LCD's involve providing a top glass sheet, generally using strengthened glass and sticking the LCD sandwich to the top glass sheet by an annular strip of double-sided adhesive foam i.e. a strip of foam with upper and lower adhesive surfaces. Generally a backing strip is peeled off one side of the foam and the foam is stuck to the LCD sandwich and another backing strip is peeled off the other side of the foam and the LCD and foam are stuck in place to the underside of the top glass.
Known arrangements for ruggedizing LCD's do not come near to meeting drop test requirements which are expected in many applications. Many general purpose contracts and government contracts require drop testing onto concrete from a height of, for example 3 feet (0.91 meters) and many military requirements call for drop testing from 4 feet (1.22 meters)
There is a need for a more rugged LCD.